The invention relates to two cycle engines with an exhaust port bridge.
In a two cycle internal combustion engine, it is known to provide an exhaust port with two openings through the cylinder wall, and with a bridge between the openings to prevent expansion of the piston rings into the exhaust port. However, when the bridge becomes heated it may expand into the cylinder which in turn interfers with the piston and causes heavy loading of the piston. One solution known in the prior art is to relieve the bridge. It is also known in the prior art to provide holes in the piston side wall for lubricating the bridge.
The present invention solves the above noted problem without relieving the bridge. A fuel-air flow passage is provided along the exhaust bridge, and a reservoir is provided between the piston and the cylinder inner wall to improve lubrication of the exhaust bridge.